The random variable x takes on the values 1, 2, and 3 with probabilities (1+3k)/3, (1+2k)/3, and
(0.5+5k)/3, respectively.
a) Find the appropriate value of k
b) Find the mean variace of x
c) Find the cumulative distribution function
a)
x
p(x)
1
(1+3k)/3
2
(1+2k)/3
3
(0.5+5k)/3
sum
For p(x) to be a probability density function
p ( x) = 1
1 + 3k 1 + 2k 0.5 + 5k
+
+
=1
3
3
3
2.5 + 10k
=1
3
k = 0.05
b)
x
p (x)
Substituting k
xp(x)
x^2p(x)
P(x)